Image forming apparatuses generally employ an electrophotography method or a direct recording method to form toner images on a recording medium. Copiers, facsimile machines, printers are the examples of an image forming apparatus.
In the electrophotography method, a toner image is formed first on a latent image carrier, such as a photosensitive drum, and then the toner image is transferred to a recording medium. Japanese Patent Application Laid-open Publication No. 2002-307737 describes the direct recording method. In the direct recording medium, a toner image is directly formed on a recording medium.
Because toner is consumed as images are formed, it is necessary to periodically replenish the toner. In general, when replenishing the toner, the old and empty toner cartridge is replaced with a new and full toner cartridge. To reduce the frequency of replacement of the toner cartridge, it is better that the toner cartridges have a larger capacity to accommodate the toner. Japanese Patent Application Laid-open Publication No. 2004-18138 and Japanese Patent Application Laid-open Publication No. 2004-139031 disclose various toner cartridges.
FIG. 16 is a schematic of a toner replenishing unit of an image forming apparatus described in Japanese Patent Application Laid-open Publication No. 2004-18138. In this conventional art, the toner cartridge is set vertically in the image forming apparatus. However, this structure limits the freedom of layout.
FIG. 17 is a perspective view of a toner cartridge disclosed in Japanese Patent Application Laid-open Publication No. 2004-139031. This toner cartridge is set horizontally in an image forming apparatus. However, this toner cartridge can be attached or detached only from the upper side of the image forming apparatus.